The disposal of hazardous waste is increasingly becoming a serious problem to industry as governmental regulations become tighter and tighter. Two leading technologies for disposing of hazardous waste are landfills and incineration. While the industry has historically preferred landfills over incineration, primarily because of cost, incineration is becoming more attractive. One reason for this is because governmental regulations regarding landfills are getting tougher. For example, in 1989 a new extended list of chemical streams banned from landfills went into effect. As industry turns toward incineration as the primary means of disposing of hazardous waste, they are also being faced with tougher and tougher incineration restrictions. For example, the destruction and removal efficiency (DRE) ratings for incineration are presently set at 99.99% for most hazardous waste, and 99.9999% for polychlorinated biphenyls (PCBs).
This has created a substantial problem for industry. For example, in the petrochemical and oil producing states, the problem of cleaning up contaminated sites and waste-oil pits are already of paramount importance, and is becoming even more acute. The quantity of waste oil contamination at oil field drilling sites has become a problem of great magnitude. The necessity of hauling the accumulated contaminated material from wide spread areas of contamination to a central decontamination site aggravates the problem considerably. Likewise, the problem of cleaning up abandoned petrochemical sites is even more severe.
The problem is particularly intense in the burning of hazardous waste. This is because not only must the waste be rapidly disposed of before harm is done to the environment, but additionally, the destruction of any potentially toxic chemicals must be sufficiently complete so that the gases which evolve therefrom are non-hazardous. To completely decompose such chemicals, relatively highly efficient and high temperature combustion is needed to lower the cost of incineration, which is typically expensive.
The discharge stack emissions from incineration are typically an important concern for several reasons. One reason is that the public views stack emission plumes with suspicion, and sometimes justifiable fears, that the incinerator operator is discharging hazardous, or toxic, gases into the atmosphere. Another reason is that federal and state authorities have regulations governing stack emissions with regular monitoring, testing, and validation to insure that prescribed emission limits are not being exceeded.
U.S. Pat. No. 5,179,903 to the inventors hereof, teaches a multistage closed loop incineration process for disposing of waste material wherein a portion of the resulting flue gas stream is enriched with oxygen and recycled to the incineration means. The remaining portion is scrubbed to remove acid gases and passed through a purification zone wherein any remaining contaminants are removed. This patent does not teach converting the waste to flue gases which are then mixed with oxygen to produce synthetic air which is used in a downstream combustion device, such as an internal combustion engine, furnace, or boiler to produce useful thermal, mechanical, or electrical energy.
Therefore, there is a substantial need in the art for improved incineration processes which are able to meet the present destruction and removal efficiency requirements, as well as requirements in the foreseen future.